1. Field of the Invention
The present invention relates to liquefied gas lighters.
2. Description of the Prior Art
Lighters of this type typically employ an expander-evaporator, designed to ensure conversion of the gas from the liquid phase in which it is stored to the vapor phase in which it is dispensed. The expander-evaporator also serves to reduce the gas pressure to a desired delivery pressure.
In order to improve the safety of these lighters, it is known to limit the maximum flame height which they can deliver by disposing a flow-limiting device upstream of the expander-evaporator.
These flow limiters, because of their location upstream of the expander-evaporator, reduce the flow of the gas in the liquid phase. A given volume of liquid gas, after evaporation, produces a gas-phase volume which is approximately five times larger. Consequently, the restriction presented by such a flow limiter must be considerable in comparison with the restriction presented by the expander-evaporator.
Therefore, when these flow limiters are made of a permeable and compressible material through which the gas passes, they must be quite severely compressed to produce a sufficient flow restriction.
In a known flow limiter, a cylindrical wick is disposed centrally of an annular rubber plug. Compressing the rubber plug compresses the wick to decrease its permeability.
In another known flow limiter, a wick is disposed around a solid rubber plug, whose deformation due to compression thereof affects the permeability of the surrounding wick.
In these known flow limiters, the forces involved can reach the point where they cause the elastic element to become permanently deformed, resulting in an unintended release of the compression exerted on the permeable wick and a corresponding increase in the maximum flame produced by the lighter. If severe permanent distortion occurs, the flow limiting effect can be completely negated.
Additionally, the powerful compression required for the elastic element means that the preregulation system must be very sturdy, excluding for all practical purposes simple adjustment by the user of the maximum flame obtainable.